Explosion-proof type switch box with alarm device

ABSTRACT

An explosion-proof type switch box with an alarm is disclosed. The box has a window opening and push buttons are provided. An ampere meter and a switch are arranged within the box adjacent the window opening and the push buttons, respectively. An indication lamp is located on the upper face of the switch, electric lamps of green and red colors being mounted at the back side of the window opening and within the indication lamp and the lamps are connected in parallel with each other. The green lamps are set to light during normal operation of a machine connected to the switch of this invention while red lamps are set to light upon occurence of any abnormal condition in the machine. Thus, the operative condition of various machines can be determined at a distance with certainty.

United States Patent [1 1 Mori [ 1 Dec.2, 1975 [75] Inventor: Shinjiro Mori, Tokyo, Japan [73] Assignee: Mori Denki Manufacturing Co.,

Ltd., Tokyo, Japan 22] Filed: Dec. 4, 1973 211 Appl. No.: 421,639

[30] Foreign Application Priority Data July 13, 1973 Japan 48-82339[U] [56] References Cited UNITED STATES PATENTS 1,704,520 3/1929 Sommer 324/103 R X 2,535,279 12/1950 Folk i 324/115 X 2,635,137 4/1953 Basham t 324/157 X 2,680,794 6/1954 Ballou 200/308 X 3,332,014 7/1967 Orths et a1 324/157 3,715,661 2/1973 Posey et a] 324/133 X 3,798,626 3/1974 Weichbrodt et a1 340/267 Primary Examiner-John W. Caldwell Assistant Examiner-Wi11iam M. Wannisky Attorney, Agent, or Firm-Wenderoth, Lind & Ponack [57] ABSTRACT An explosion-proof type switch box with an alarm is disclosed. The box has a window opening and push buttons are provided. An ampere meter and a switch are arranged within the box adjacent the window opening and the push buttons, respectively. An indication lamp is located on the upper face of the switch, electric lamps of green and red colors being mounted at the back side of the window opening and within the indication lamp and the lamps are connected in parallel with each other. The green lamps are set to light during normal operation of a machine connected to the switch of this invention while red lamps are set to light upon occurence of any abnormal condition in the machine. Thus, the operative condition of various machines can be determined at a distance with certainty.

2 Claims, 4 Drawing Figures US. Patent Dec. 2, 1975 Sheet 1 of2 3,924,255

US Patent Dec. 2, 1975 Sheet 2 01'2 3,924,255

EXPLOSION-PROOF TYPE SWITCH BOX WITH ALARM DEVICE BACKGROUND OF THE INVENTION This invention relates to a pressureand'explosionproof type switch, and more particularly to a switch wherein it is possible to observe an operative condition of machines connected to the switch through a window opening provided on the front face of the switch and by means of the color of electric lamps adapted to light in an indication lamp provided on the upper wall of the switch.

Various electrical machines currently indicate, by means of electric lamps of green and red colors, whether the machines are operating normally or not. When the red lamp lights indicating a dangerous condition of the machine, operation thereof is stopped for inspection and the abnormal condition is remedied, thereby securing safety of the machine.

However, there have been no such preservative facilities in pressureand explosion-proof type switches. As well-known, explosion-proof type electrical machines are used in places where a possibly dangerous explosion may occur and full consideration must be taken to preservative facilities. It is true that various machines of explosion-proof type have been manufactured and used against the danger of explosion, but no development has been made in devices for deciding the operative state of the machines connected to switches.

SUMMARY OF THE INVENTION This invention is directed to a-pressureand explosion-proof type switch provided on its front wall with a window opening through which a pointer of an ampere meter can be read out. Two electric lamps of green and red colors respectively are positioned on the back side of the window opening, an indication lamp is mounted on the upper wall of the switch body, and two electric lamps are connected in parallel with said two lamps in the window opening and are mounted inside the indication lamp in such a manner that electric lamps of the same color are lit simultaneously so that the green electric lamp may light when the machines connected to the switch operates normally while the red electric lamp may light when an abnormal condition occurs in the machine.

It is therefore an object of this invention to provide a device capable of detecting an operative condition of the machines connected with the device by the pointer of the ampere meter viewed from the window opening and which also detects the operative condition of the machines and produces an indication which may be viewed at a distance by lighting the window opening in green or red color.

It isanother object of this invention to provide a switch capable of providing indications as to a number of machines at a time by lighting in the indication lamp provided on the upper surface of the switch body electrical lamps connected in parallel with the lamps provided in the window opening.

A further object of this invention is to provide a switch having a device for detection of an abnormal condition, in which a screen is mounted on an arm extending towards the pointer of an ampere meter so as to synchronize therewith, a neon lamp and CdS (a cadmium photoconductive cell) are provided at the front and back sides of the screen, and a change in a current flowing through the cadmium photoconductive cell, which occurs upon interruption of light from the neon lamp by the screen, is transmitted to a relay circuit to actuate the same so that the electrical lamps of green and red colors are switched.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view of the switch,

FIG. 2 is a longitudinal sectional view of the switch of FIG. 1 taken along a central line of the front surface thereof,

FIG. 3 is a wiring diagram of the inside of the switch, and

FIG. 4 is a perspective view illustrating the mecha nism for detection of movement of the pointer of the ampere meter of FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION A switch body 1 is of pressureand explosion-proof structure, and the whole body is manufactured by casting. The switch body 1 has a box shape and is provided with a window opening 2 and push buttons 3,4 on its front face. The push buttons are of such structure that depression of one of them sets the switch to an ON state and that of the other turns it to an OFF state. There is an opening leading to a guide tube 1a in a bottom wall of the body 1. A wire of a machine connected to the switch body extend through the guide tube la.

The window opening 2 is provided with a recess 2a on the back side inside the switch body and a transparent plate 5 made of acrylic resin is put into the recess. A frame body 6, formed in the shape of a picture frame is superposed on the transparent plate and fixed therein by bolts 7.

The switch body 1 has an auxiliary board 8 for mounting various devices and an ampere meter 9 is mounted adjacent the window opening 2 on said auxiliary plate 8. The ampere meter 9 is so arranged that the pointer 10 thereof can be read through the transparent plate 5.

The switch body 1 is provided on the upper surface lb with a hole into which an indication lamp 12 is fixed. The auxiliary board 8 has an extension 8a with a socket 13 into which two electric lamps l4 and 15 of green and red colors, respectively, are put. A protective mesh 16 is arranged on the surface of the indication lamp 12 for protection thereof.

On the back side of the window opening 2, sockets 17 are mounted at upper and lower parts of recess 2a and electric lamps 19 and 20 of green and red colors, respectively, are put into these sockets 17. These two lamps are connected with the electric lamps arranged in the indication lamp in such a manner that two lamps of the same color are connected in parallel with each other. It follows therefore that the indication lamp and the window opening always emit the same color.

A box 21 for accomodating the relay circuit is provided under the ampere meter 9 on the auxiliary board.

Boxes 22 and 23 are also provided for accomodating the switches at the positions corresponding to the push buttons 3 and 4 on the auxiliary board 8.

The switch according to this invention is connected with an electrical machine such as a motor (not shown) and electrical connection is made with the machine by depressing the push button 3. The amount of current supplied to the machine is indicated by the pointer 10 of the ampere meter 9 and by observing the movement of the pointer from the window opening 2 a determination as to whether the machine is operating normally or not may be made. At the same time, it is possible to decide at a distance whether the machine is normally operating or not, as the green lamps 14 and 19 are lit so that they illuminate the window opening 2 and the indication lamp 12 with green color.

When an abnormal event occurs in the operation of the machines, the red lamps l and 20 are lit by operation of the relay circuit inside the box 21. It is, of course, noted that the ampere meter 9 indicates abnormal consumption by its pointer. However, occurrence of an abnormal event is more clearly shown by illuminating the entire window opening and the indication lamp with red color.

FIGS. 3 and 4 show how to switch electrical lamps according to a change in the consumption electric power. In FIG. 4, it is noted that the pointer of the ampere meter 9 is bent at a right angle in front of scale 91. The pointer 10 is secured to spindle 92 which has an arm 93 extending toward the pointer 10. A screen 94 is fixed on the arm 93 for interrupting light. The scale 91 and the screen 94 are each in the form of a circular arc with a center at the spindle 92. A neon lamp 95, always lit, is located at one side of the screen 94 and a photoconductive cell (CdS) 96 made of cadmium sulfide the value of current produced by the photoconductive cell will change depending upon the strength of light.

FIG. 4 shows an arrangement wherein the screen 94 is located just in front of the neon lamp 95 and interrupts the light therefrom, and which indicates a dangerous condition. At this very instant, the pointer 10 reaches approximately half of the scale 91 and this may be a rate current value. The position of the neon lamp and the photoconductive cell may be changed.

Referring to FIG. 3, the ampere meter 9 is supplied with a voltage through lines 101 and 102 which is stepped down for easy measurement. The supply source of the circuit is obtained by connecting the power source supplied to the machine to the primary side of a transformer 105 through lines 103 and 104. The neon lamp 95 is connected to the primary side of the transformer 105 through lines 106 and 107, thereby lighting the neon lamp.

Lines 108 and 109 are connected to the photoconductive cell and each has one end connected to the moving iron of a relay 110 and its other end connected to the moving iron of the relay through a transistor. The secondary side of the transformer 105 has one end connected to the moving iron of the relay 110 and its other end connected through a line 111 to the junction point 112 between respective ends of the green lamp l9 and the red lamp 20. The other lines 113 and 114 leading to the green and the red lamps are connected to the contact b and the contact a of the relay 110, respectively. The moving contact of the relay is connected to the line of the secondary side of the transformer.

The electric lamps in the indication lamp 12 of the switch body 1 have respective lead-in lines 111a, 113a and 114a, each connected in parallel with the lines 11 l, I I3 and 114, respectively, so that the window opening and the indication lamp will light simultaneously with lamps of the same color.

In the state as shown in FIG. 3, light from the neon lamp 95 is interrupted by the screen 94 and the current from the photoconductive cell becomes weak, with the result that the moving iron of the relay I10 loses exciting force and the moving contact thereof remains in contact with the contact a. In this situation. line 111 is connected with line 114 and thus the red lamps 15 and 20 are lit. If the screen 94 moves back to the position where light from the neon lamp is not interrupted, or upon removal of the abnormal condition of the machine, the current from the photoconductive cell increases and excites the moving iron with the result that the latter makes contact with the contact b and the green lamps l4 and 19 will light.

The switch, the operation of which has been described above, is capable of controlling the operative condition of machines by a pointer of an ampere meter and electrical lamps arranged in the window opening and the indication lamp, and therefore insures confirmation of safety of the machines.

I claim:

1. An explosion-proof switch box with an alarm device for indicating an operating condition of a machine, and comprising:

an explosion-proof body having a front surface with a window opening therein, a botton surface with a guide tube therein providing means for passage therethrough of an electrical connection between said body and a machine, and an upper surface having a hole therein;

a transparent plate positioned in said window opening;

an ampere meter positioned within said body adjacent said window opening and having a pointer visible through saidtransparent plate, said ampere meter being connectable to said machine;

first and second pushbuttons mounted in said front surface of said body;

first and second switch means, positioned in said body and connectable to said machine and connected respectively to said first and second pushbuttons, for respectively establishing and breaking electrical connection with said machine;

a relay circuit positioned in said body and connectable to said machine;

first light source means extending through said hole in said upper body surface for exhibiting light of a first color;

second light source means extending through said hole in said upper body surface for exhibiting light of a second color;

third light source means positioned behind said transparent plate for exhibiting light of said first color through said entire transparent plate;

fourth light source means positioned behind said transparent plate for exhibiting light of said second color through said entire transparent plate; said first and third light source means being electrically connected in parallel to said relay circuit;

said second and fourth light source means being electrically connected in parallel to said relay circuit; and

detection means, operatively connected to said ampere meter and said relay circuit, for detecting first positions of said pointer indicative of a first range of operating conditions of said machine and generating a signal to cause said relay circuit to energize said first and third light source means and to deenergize said second and fourth light source means, and for detecting second positions of said pointer indicative of a second range of operating conditions of said machine and generating a signal to cause said relay circuit to energize said second and fourth light source means and to deenergize said first and third light source means.

2. An explosion-proof switch box with an alarm device as claimed in claim 1, wherein said window open- 

1. An explosion-proof switch box with an alarm device for indicating an operating condition of a machine, and comprising: an explosion-proof body having a front surface with a window opening therein, a botton surface with a guide tube therein providing means for passage therethrough of an electrical connection between said body and a machine, and an upper surface having a hole therein; a transparent plate positioned in said window opening; an ampere meter positioned within said body adjacent said window opening and having a pointer visible through said transparent plate, said ampere meter being connectable to said machine; first and second pushbuttons mounted in said front surface of said body; first and second switch means, positioned in said body and connectable to said machine and connected respectively to said first and second pushbuttons, for respectively establishing and breaking electrical connection with said machine; a relay circuit positioned in said body and connectable to said machine; first light source means extending through said hole in said upper body surface for exhibiting light of a first color; second light source means extending through said hole in said upper body surface for exhibiting light of a second color; third light source means positioned behind said transparent plate for exhibiting light of said first color through said entire transparent plate; fourth light source means positioned behind said transparent plate for exhibiting light of said second color through said entire transparent plate; said first and third light source means being electrically connected in parallel to said relay circuit; said second and fourth light source means being electrically connected in parallel to said relay circuit; and detection means, operatively connected to said ampere meter and said relay circuit, for detecting first positions of said pointer indicative of a first range of operating conditions of said machine and generating a signal to cause said relay circuit to energize said first and third light source means and to deenergize said second and fourth light source means, and for detecting second positions of said pointer indicative of a second range of operating conditions of said machine and generating a signal to cause said relay circuit to energize said second and fourth light source means and to deenergize said first and third light source means.
 2. An explosion-proof switch box with an alarm device as claimed in claim 1, wherein said window opening on said front surface of the body is provided with a recess in which said transparent plate is positioned; and further comprising a frame body superposed on the outer side of said transparent plate and secured to said body by means of bolts. 